Critical Nitrogen Dilution Curve and Nitrogen Nutrition Index for Summer-Maize in North China Plain

Abstract

In order to verify the applicability of critical nitrogen (N) dilution curve for summer maize in North China Plain, and the feasibility of N nutrition index (NNI) in evaluating N nutrition status of maize plant, a 2-year experiment with five N-fertilizer treatments (0, 60, 120, 180, and 240 kg N ha –1 ) was conducted using the cultivar Zhengdan 958. The results showed that the above ground biomass (W) increased significantly with increasing N-fertilizer application within a certain range. The data of above ground biomass and corresponding N concentration for each sampling stage were divided into N limited group and N non-limited group based on the statistical results, then the critical N concentration (N c ) was calculated and the critical N dilution curve model (N c =34.914W –0.4134 ) for summer maize was established, and the model parameters had a good similarity to these reported. NNI calculated based on the critical N dilution curve model had a significant correlation with relative N uptake amount, or relative above ground biomass or relative yield. Therefore, critical N dilution curve and NNI can be used to predict plant N c and characterize plant N status in summer maize in North China Plain.